Do I have a bad brake bleeder nipple?

Ugh. This is so frustrating! After rebuilding my M/C, putting new brakelines on, and rebuilding my brake calipers, I've run into the problem of replacing the brake fluid! What the heck?

I started with my MityVac, but I kept getting air in the fluid, so gave up. I chalked it up to having a poor seal over my bleeder nipple, but that was probably wrong.

So then I went to the manual way - fill up the MC, open the bleeder nipple on the calipers 1/3 turn (with clear drainage tube attached), pull the brake handle in, close the nipple, release the brake handle, and repeat. After moving a few ounces of brake fluid through, I'm still seeing some tiny air bubbles coming out with the fluid. And at one point, some fluid leaked out around my bleeder nipple during the process. Oh, and I'll mention this is a new nipple, and I put a small amount of threadsealer on it when I installed it.

So... could it be that the problem with air in the system lie in the bleeder nipple itself? That it's pulling in air around its threads? There appears to be no leaks around my banjo bolts, and I've kept the MC fluid covering the bottom. I see no other place air could be getting in.

Unless a member give me a better way to proceed, I'm going to reinstall the old bleeder nipple and give that one a try.

It's worth mentioning that this is the first time I'm doing this... so no doubt, there's significant human error involved! But gee, I thought I knew what I was doing.

It's finally a sunny day outside in Minnesota after an awful wet month of May, and I can't ride! Ugh!

 

When the bleeder is cracked there will be some air that leaks past the threads; it's unavoidable. Keep using the Mity-Vac, but pay no attention to the steady stream of tiny bubbles (those are from the bleeder fitting), just look for the larger bubbles from the brake lines.

The way bleed nipples seal is by pressing their angled face (at the bottom of the fitting) against the angled seat that is machined into the bottom of the threaded fitting hole. All that the threads do is pull the angled faces together. The threads are not airtight (and can't be). Don't use thread sealer on the bleeders; you can do a single wrap of teflon tape to cut down on the amount of air you see while bleeding with a vacuum tool. Thread sealer can make it very difficult to crack the bleeders open again, and may result in the rounding off of the bleeder "nut".

 

Thanks k-moe. Now, as I pull the fluid down through the lines with the Mity-vac, do I need to work the brake lever at all?

I guess I honestly don't know how the MC works - in other words, when fluid is pulled down through the tiny hole, versus the larger hole. I'm only guessing that the larger one is the "send" hole, and the tiny one the "return" hole.

 

I tried again this evening with the Mity-Vac, and in total, I've put 10 ounces of brake fluid through the lines without getting pressure (or no air bubbles) so obviously, something ain't right!

Again, I have no fluid leaks anywhere, and have always ensured that the drain holes in the MC stay covered. So, isn't it possible that I didn't reassemble my MC piston correctly? Would that cause my problem and my inability to get any pressure in my lines? Here's a picture of the old piston on the left, and my new one on the right. I mean, my seals are on there correctly, aren't they?!



Here's a close-up view of the new piston by itself, as I just yanked it out:



If this still doesn't work, I'll film it!

 

take that bleeder nipple out and you'll see a tiny hole on the beveled end.
wrap the threads with a few wraps of teflon tape but don't cover the tiny hole, screw it back in and the bubble problem should be gone. wrap it on turning the bleeder clockwise. when your done just tighten it down and leave the tape on it.
try flopping the wheel so a bubble in the wheel cyl would go towards the bleeder hole

 

One more suggestion. Go to your local farm/ hardware store. Get a large syringe (WalMart and True Value have one for measuring 2 stroke oil that works well if you have no farm store nearby), and a length of clear tubing that will fit over the end of the syringe, and fit snugly on the bleed nipple. Fill the syringe with brake fluid (leave the master cylinder empty) and pressure fill the system from the caliper end.

The air will tend to work it's way up (there are some "air traps" in the calipers that are the result of how the passages were drilled) into the master cylinder, and out of the system.

GO slowly. There is some risk of making quite the mess if you try to rush.


also......did you use all new crush washers when you put the lines on? Did you accidentally get one out of place? Just trying to eliminate all potential causes of air leaks.

 

Inspect the BORE of the Master Cylinder.

Pitting and accumulated Crud will nix any chance of Bleeding the System.

 

Yes Rick, I inspected the bore after I meticulously cleaned it and it was beautiful.

To answer K-moe's question, yes, I used all new crush washers when I installed the new brakelines, and all banjo bolts were torqued to factory specs. But I'm assuming that if air was getting in somewhere along the lines, I'd also be seeing a fluid leak at the same place.

What irritates me about the Mity-Vac system is that the attachments shown below do not seem to create a very good seal around that bleeder nipple:


As a result, I've been using a clear tube instead at the nipple end. Looking at the picture above though, I see that upon close inspection, the ends are somewhat different. I had better go back and make sure I was using the tightest one possible.

To me, I see the biggest "problem area" in the brake system to be the area directly behind the caliper piston. I assumed I was OK in shoving that piston all the way back when I reinstalled it - I have no idea how much volume of brake fluid exists between the caliper wall and the piston when in the relaxed or non-braking mode.

Not sure what to try next, so maybe I will try K-moe's idea of backfilling the system.

 

When you have the nipple closed do you have a firm lever? Any resistance at all? These can be a PIA to bleed.

 

Nope - I was never able to build up pressure in the lever. That's why, for whatever reason, I decided to take my MC apart again.

 

You gave up too soon. I went through this with both of my 550 Secas. I'll give you some more ideas when I get home (too much to type right now.)

 

The syringe method works well. Once you have the piston working you can also pump the fluid back into the syringe in case you feel there might still be air in the caliper.

 

OK, got a minute.

You just gave up too soon. Polock's advice about the proper way to wrap the bleed screw is right on; you absolutely need to do that. Especially if using a Mity-Vac.

I didn't use the Mity-Vac "coupling" I used one of the tube-to-tube thingies and put an appropriate sized piece of tubing directly on the bleeder nipple.

I have gotten the best results by using my Mity-Vac followed by old school hand-pumped bleeding.

Be sure the tiny hole in the bottom of one of the "false" drillways in the M/C is clear. Use a bristle from your parts cleaning brush to poke thru it.

Bleed the thing as best as you can; the blasted tiny bubbles will NOT stop. Make sure the M/C is full, put the cap back on and pull the lever to the bar, and wrap a bungee cord around it and go do something else until tomorrow.

When you get back to it, you should at least be able to bleed it functional. The only way to get it truly and completely bled is to do it again after a couple hundred miles and a few "heat cycles." You'll get a nice fat bubble, guaranteed.

My theory is that the rough machining in the caliper bore traps "microbubbles" in the grooves that simply need TIME to migrate together and be able to be bled out.

I've worked on countless hydraulic disc systems on many different makes of bikes over the years and have never had as much trouble bleeding brakes as with the '80s Yamahas. I had a couple back in the day that I put stainless lines on and went thru this back then too.

 

Many thanks Fitz. I'll follow your instructions to the letter and report back on my success.

Great to know that others have struggled with this, because while I've heard that bleeding brakes was often a pain, I didn't expect quite this much of a PITA.

Merci from Minnesota!

 

I fail to understand "The Syringe Method".

The Main Master Cylinder Hydraulic Seal is a ONE WAY Seal.
Fluid is NOT supposed to seep beyond the Main Hydraulic Seal at all.

Sometimes the BEST Method is the "Old tried and true".

Wrap the Bleeder with Teflon and open the Bleed Orifice.
Fabricate an AIR TIGHT Bleeding Hose.
(2 Inches of Rubber Vac Line <> Coupled to Clear Vinyl Hose.)

Submerge the Bleeding Hose in a Jar containing Brake Fluid.
(Weight the Hose to KEEP the end SUBMERGED.)

Build some pressure by Working the Brake Lever.
(Use an assistant)
When pressure develops, ... OPEN the Bleed Nipple
HOLD the Brake Lever and let the Caliper evacuate.
Close Bleeder.
Pump.
Repeat.

Brake Fluid should not RETREAT back into the Caliper.
The M/C should PUMP Fluid down the Line out the Bleeder.

I don't understand how it is possible to develop enough pressure using the Syringe to FORCE Fluid and Air UPWARDS.

The process relies on Fluid and Air being evacuated Down and Out.

Most PRESSURE TYPE Fluid Bleeders operate by connecting the Under-pressure volume of Brake Fluid, to be introduced to the system, through the M/C by employing a device that substitutes for the M/C Cover.

 

I followed BigFitz's advice, but still no-go. I let it gravity bleed for several days, actually, and did the Mity-Vac route, but I could never get a steady stream of fluid.

I wasn't suppose to leave the brake level pulled in during the bleed, was I? I didn't do that.

Then, the handle feel off the Mity-Vac. So, I was back to the manual method - open the nipple, pull in the brake lever, close the nipple, release the brake lever, and repeat. I moved a fair amount of fluid (maybe 4x my MC capacity), and it still is not under enough pressure. Currently, when the brake lever is pulled, the caliper piston will move the brake pad about half the way to the disk, but that's it.

So... any other input in troubleshooting? I did just PM a fellow local XJ member to see if a in-person visit might save me from giving up.

 

Do your self a favor, ...

Pull the Master Cylinder's Cover.
Remove the Rubber Gasket.
Squeeze the Brake Lever.

IF Brake Fluid shoots-up in a fountain-like stream ... looking like the Dancing Waters outside the Bellagio Hotel and Resort in Las Vegas ...

The Seals in the Master Cylinder are dead, shot, beat, cooked, Foo-bar!
All the Kings Horses and all the Kings Men,
Won't be able to develop Hydraulic Pressure again.

"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein

 

Well, this was all part of a complete overhaul of my brakes, so I had just rebuilt my MC with all new seals. However, YES, if hold the cover up and squeeze the brake, a small line of fluid will shoot up an inch or two - it's hard to know how high it would go because I'm holding the cover over it to avoid the fluid going everywhere!

So, it shouldn't be doing this at all? I need to replace these new piston seals?

 

No, if you pump the lever with the lid off you'll get a small geyser. Your M/C is likely fine, you haven't got it bled yet is all. Only 4X the reservoir capacity is nothing; you'll likely run a whole bottle of brake fluid through it in this process.

First off, pull the caliper over (to the outside) so the "fixed" pad is tight against the disc on the backside.

Then, bleed as you were. In the "leave it overnight" scenario, the lever should be left pulled, yes. I wrap a cloth bungee cord around it to keep a pull going.

 

OK - roger that I'll move a lot of fluid through this before it's all bled of air.

Sorry to ask again, but does the brake lever remain pulled in the whole time if I'm using the Mity-Vac route?

 

The Dancing Waters at the Bellagio aren't small geysers.

If you squeeze the Brake Lever and a stream of Fluid leaps out of the reservoir, ... you got troubles.

If it squirts HARD out of there, ... the Main Seal is Leaking-by.

When the Main Seal FAILS to Pump Fluid into the System and Pressure develops BEHIND the Main Seal, ... the Cylinder Seal FORCES Fluid to be expelled through the Replenishment Orifice. Big time.

When the Main Hydraulic Seal is Good, Fluid within the MC is Pumped down into the System.
Very little Pressure behind the Main Seal results.
As the Brake Pads wear and more Fluid is needed in the System, ... The Cylinder Seal PUSHES Fluid through the Orifices in the Piston behind the Main Seal ... which provide LESS Resistance than the tiny Replenishment Orifice.

 

The lever doesn't need to be pulled for when you use the Mity-Vac, no.

Getting my Secas brakes bled was one of the most frustrating things I've ever done, mechanically; and I've been at this a good long time.

I used a combination of the Mity-Vac, holding the lever back overnight, and LOTS of good old conventional hand bleeding. And it still took forever. Both bikes.

 

This is comforting to know! OK - chin up, and I'll continue trying after work today!

 

your doing this with the cover on? how can you tell if any bubbles are coming out?
think about this, there's a bubble say a 1.5 inch long partly in the MC the rest in the line just outside. you pump the lever, the bubble and some fluid move down the line. you do the hold, open, close thing, 5 times, where is that bubble? every time your not pumping, that bubble is going back up the line.
this worked for me after it set for awhile.
take off the cover, cover the tank with plastic and a rag just in case, now "wiggle" the lever, pull it slowly back 1/2 inch then let it snap back, you should get some tiny bubbles out of the relief hole, don't give a full pump and drive the air down the line, just a little "wiggle" to agitate it. when it snaps back theres a short time the piston will suck fluid and air back from the line. go do that about 50 times, i bet you get pressure.
4 MC's aint nuthin, i used almost a quart before i figured that out

 

Yes, I've been leaving the cover on (without the rubber gasket) while I've being drawing fluid through the system. Between pumps, I check the fluid level of course to make sure I don't empty it! But no, I was only looking for bubbles to come out the bleeder nipple, not bubble up in the MC.

But sure Polock, I'll try what you said in case a bubble is stuck around the MC. I'll try ANYTHING and EVERYTHING at this point!

We are finally getting some sunny weather this week in Minnesota!

 

after a few hours air is going to be in the highest point in the system, make the hoses bend or twist the MC so that point is the MC.
think like a bubble, that's not hard for me

 

and .. turning the wheel so the bleeder is at it's highest point, helps too, maybe on side stand

 

true, if your going to suck from the bottom (that sounds bad), but if your letting the air rise to the MC the line fitting needs to be higher

 

::SndF/X:::
(Phone ringing)

"Hello. This is Forrest. Forrest Gump."

"Well congratulations Forrest. If you answer the Jackpot Question; you win a box of chocolates. Ready?"
"What's it about?"
"It's about Japanese motorcycles."
"O.K. I hope I win that box of chocolates. I hope its one of them box of chocolates with the what-kind-it-is sheets."

"For a box of chocolates."
"Wait. How long do I have to answer?"
"You get exactly one New York Minute."

"Should it take more or less than than eight days to get the front brakes bled on a Yamaha XJ-Bike?"

 

I don't know if this applies to the 550 MC, but on the 1100's, if you squeeze the brake lever in ALL the way, as you would with a fresh rebuild, it inverts the rubber cup at the end of the piston, and you will never get a hard lever. The answer is to take the piston back out, fix the cup, and start the process again, this time putting a block of wood between the lever and the grip, so that you cannot bottom out the piston.
CZ

 

I love you guys. In the midst of all the frustration, Rick made me laugh.

So, for your collective enjoyment, I've uploaded a video (yes! Grab a paper bag and start breathing into it to contain your excitement!) of my continued attempt.... (cute soap opera music...) to bleed forementioned brakes:
http://www.youtube.com/watch?v=qC4yOphF ... e=youtu.be

Now please, don't share this link with all your friends! I don't want for it to go viral!

Now, I don't know what's changed, but you can see that I'm really only getting air out of there now, and no fluid, and the MC level is staying steady. This change just happened at the end; before that, I refilled the MC a few times.

But, the good news is that the front brake will now fully close. Hard to know how much pressure is there until I actually try to run it, but I don't really want to do that quite yet.

In answer to some previous post, yes, because it's on a centerstand, I think the connection at the MC is a hair higher than the ports in the MC, so an air bubble could be stuck there. Tomorrow, I'll try putting it on the sidestand (unless other advice is suggested...) and keep moving brake fluid through this thing.

 

I want to read the final chapter in this story

 

Yeah... so do I Polock! So, I didn't get any comments on my video, so I once again hooked up my Mity-Vac yesterday after I adjusted the handlebars as best I could to try to ensure that bubbles will be able to rise to the MC. I also worked the MC piston a few times in the hope of dislodging any bubbles that might be trapped there.

Anyways, I hooked up the Mity-Vac and got the same experience as shown in the video - just looked like air to me. But here's the thing: once I gave up on that, and went to the manual method of opening the nipple, pressing in the brake lever, closing the nipple, releasing the lever, etc, I got a good, solid stream of fluid with no bubbles in my draining tube! Well, one tiny one... So after 4 cycles, I closed it off and took it for a ride.

The brakes will close, but while there's pressure and I do get some braking, it's obvious that I don't have the braking I should. So, my assumption is that there's still air in there, and I should go back to the manual method and do a bunch of cycles in the hope of purging any of that leftover air. Sound appropriate?

Incidentally, I just regret I don't have someone to take pictures of my whole building of my MC, calipers, and replacing the lines.. I'd like to contribute to the group with a FAQ.

 

Run it through a few "heat cycles" and re-bleed. YOU'VE WON at this point, now it's just a case of "tidying up."

 

"bad brake bleeder nipple"

Say that 5 times fast... ouch

 

c) Finally, here's one neat trick to get a truly professional, world-class level of brake bleeding accomplished: after you "finish" your final bleeding cycle, turn the forks so that the caliper you are bleeding is on the high side. Now do one final bleeding to rid the system of the last few tiny bubbles that tend to hide in the top of the caliper when the front wheel is straight ahead. The reason for this is: if you look at where the bleeder screw is on the caliper body, it is placed just slightly below the very top arc of the piston bore in the caliper. Turning the front wheel gets the internal bleeder screw port above this arc, and allows you to get all that pesky air out of your system.

 

That too.

On a single-caliper bike like the 550s, I just bleed in that position from the beginning. With the Euro bar, full left lock also provides a relatively level M/C reservoir.

 

For my clarification purposes: I understand to position the MC and caliper is such a way to try and dislodge the air bubbles, but am unclear if all those bubbles are expect to be extracted solely through the bleeder nipple. If any are stuck around the MC, are those ever "floated" up?

 

Yep. Or forced out the bottom end with the GALLONS of fluid you've pumped through it.

TIME is the biggest factor; it simply takes time for the microbubbles to "find each other" and become one big, bleedable bubble.

 

I don't know where you get these crazy ideas, that a bubble would go up and come right out the relief hole with a little coaxing. That's what's wrong with this inerweb thingy

 

Well, if a bubble is sitting just below the MC, I could see it making its way up..

Other than that, my crazy ideas come from the place that got me to invest all my retirement funds into a new breakfast cereal idea - braille alphabits. ;-)

 

I have never failed to successfully bleed Front Brakes by Pumping Fresh Brake Fluid down through the Calipers using the Pressure developed by a healthy Master Cylinder.

I have my lovely wife on the Brake Lever manipulations and keeping the M/C Reservoir filled-up at least half-way.

I use a high-quality "One Man Bleeder" I bought from the MAC Tools guy many moons ago.

Initially, I have her slowly pump the Brake Lever until the Hose fills and Fluid squirts-out the Check-valve.
Once the Fluid starts squirting-out the one-way; I build-up Pressure and open the Bleeder ...
Letting the Line evacuate any Air left in the System.

If you can't develop Hydraulic Pressure enough to MOVE Brake Fluid out of the Bleeder along with any Bubbles in the works, ...
No pressure.
Spongy Lever.
No Leaks evident ...

Shine the Spotlight on the --> Master Cylinder.

How do I know if my Master Cylinder's bad?

1) "Heavy Fountaining.
2) Won't pump up.

Troubleshooting:

Remove the MC Banjo.
Install short Metric Cap Screw.
Loose Screw Bleed MC.
Tighten Cap Screw.
TEST Lever for Pressure.

If the MC is good and there are NO Leaks ...
The whole job shouldn't take more time than 1.5 Hrs.

Without using a Mighty-Vac.
Or any other unconventional methods.

 

yea, like he said. i might add, everything in life should be such a pleasurable and rewarding experience